External material lifters for rotary kilns and the like

ABSTRACT

An apparatus is disclosed for heating, drying or otherwise treating a raw material or a slury of raw material that is lifted and showered back down to a bed of the material while a treating gas passes through the showering material. The apparatus includes a tubular shell mounted for rotation about a slightly inclined central axis. A plurality of material lifting buckets are spaced around and attached to the outer circumference of the rotary shell to rotate with the shell. Each bucket has side wall means with a terminal lip attached to the shell in alignment with a radial opening through the shell, and an end wall opposite the lip. Reference is made to a first portion of the bucket wall means and lip. The first portion of each bucket is defined as the portion which is lowermost on the upturning side of the shell and uppermost on the downturning side of the shell. Each bucket is attached to the shell with the defined first portion of the bucket defining an acute angle with the shell and providing a material retaining pocket between the first portion and the end wall which when the bucket is on the upturning side of the shell, locates the pocket below the lip until the bucket is carried a substantial distance above a horizontal plane through the central axis of the shell. The smaller the defined acute angle the higher the bucket will travel before spilling and dumping the last of the material in the pocket to shower back into the shell.

United States Patent [191 Dandois Jan. 1,1974

[ EXTERNAL MATERIAL LIFTERS FOR ROTARY KILNS AND THE LIKE Charles E. Dandois, Milwaukee, Wis.

[73] Assignee: Allis-Chalmers Corporation,

Milwaukee, Wis.

[22] Filed: Nov. 28, 1972 [21] Appl. No.: 310,161

[75] Inventor:

Primary ExaminerJohn J. Camby AltomeyArthur M. Streich et al.

[57] ABSTRACT An apparatus is disclosed for heating, drying or otherwise treating a raw material or a slury of raw material that is lifted and showered back down to a bed of the material while a treating gas passes through the showering material. The apparatus includes a tubular shell mounted for rotation about a slightly inclined central axis. A plurality of material lifting buckets are spaced around and attached to the outer circumference of the rotary shell to rotate with the shell. Each bucket has side wall means with a terminal lip attached to the shell in alignment with a radial opening through the shell, and an end wall opposite the lip. Reference is made to a first portion of the bucket wall means and lip. The first portion of each bucket is defined as the portion which is lowermost on the upturning side of the shell and uppermost on the downturning side of the shell. Each bucket is attached to the shell with the defined first portion of the bucket defining an acute angle with the shell and providing a material retaining pocket between the first portion and the end wall which when the bucket is on the upturning side of the shell, locates the pocket below the lip until the bucket is carried a substantial distance above a horizontal plane through the central axis of the shell. The smaller the defined acute angle the higher the bucket will travel before spilling and dumping the last of the material in the pocket to shower back into the shell.

2 Claims, 5 Drawing Figures EXTERNAL MATERIAL LIFTERS FOR ROTARY KILNS AND THE LIKE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to tubular shell rotary kilns, dryers and the like and in particular to such apparatus provided with lifters for scooping material from a bed within the shell and dumping the material as the shell is rotated, with the dumped material falling as a shower through which heated gases are directed to pass.

2. Description of the Prior Art Rotary tubular shell kilns and dryers have long utilized lifters projecting radially inward from the inner circumference of the shell and a liner within the shell, to lift materials from the bottom of the shell and then shower the material through the gas stream passing axially through the shell. Examples of such dryers and kilns are shown in US. Pat. No. 1,332,137 of 1920, US. Pat. No. 2,825,149 of 1958 and US. Pat. No. 2,924,513 of 1960. Kilns and dryers with such lifters do achieve better heat transfer than is achieved by merely passing heated gases over a churning bed of material in the bottom of the rotating shell. However, because such lifters may themselves be exposed directly to very high temperature gases passing through the shell, as is the case for example in cement kilns, in order to achieve reasonable life expectancy for the lifters, the lifters cannot be located as close to the burner flame as is desirable from a heat transfer point of view. Even in lower temperature as occurs with dryers, the gas temperature high enough to affect the life expectancy of lifters and in case lifters projecting into a rotating shell interfer with the desired flow of gas through the shell.

The disadvantages associated with lifters projecting into a rotating shell are substantially lessened by providing lifters only partly within the shell and partly out side the shell, as shown in US. Pat. No. 2,815,940 of 1957. However, in the arrangement shown in this prior art patent the lifters within the shell cannot be completely eliminated in order to avoid the external lifters emptying so quickly that material would not be lifted high enough to provide the desired shower of material across the kiln. It is to this problem that the present invention is directed.

SUMMARY OF THE INVENTION It is among the objects of the present invention to provide rotary tubular shell kilns, dryers and the like, with new and improved material lifters that are entirely external of the shell and provide a pocket for retaining a portion of material lifted from the bottom of the shell until it is lifted substantially above the horizontal level of a central axis through the shell. Another object of the present invention is to provide such external lifters that can be provided with an adjustable volumetric capacity. 1

According to a preferred embodiment of the present invention a rotary tubular shell, such as a cement kiln, is provided with a plurality of material lifting buckets spaced around and attached to the outer circumference of the rotary shell to rotate with the shell. Each bucket has side wall means with a terminal lip attached to the shell in alignment with a radial opening through the shell, and an end wall opposite the lip. The bucket side wall means and lip have a portion, hereafter referred to as a first portion, which comprises the lowermost portion of the side wall and lip of a bucket when being carried upwardly by the rotating shell and this same portion comprises the uppermost portion of the side wall and lip of a bucket when being carried downwardly by the rotating shell. Each bucket is attached to the shell with this first portion of the bucket defining an acute angle with the shell and providing a material retaining pocket between the first portion of each bucket and the end wall of each bucket, which when the bucket is on the uptuming side of the shell, locates the pockets below the lip until the bucket is carried a substantial distance above a horizontal plane through the central axis. Thus, this invention insures that a substantial portion of the material lifted from the bottom of the shell will be lifted high enough to provide a shower of material across substantially the entire diameter of the shell. Further, according to the present invention, the buckets may be provided with an end wall that is movable toward and away from the shell to regulate volumetric capacity of the bucket, or the bucket may be tapered toward an apex point in space radially outward of the shell to provide for rapid and smooth flowing discharge of material from each bucket when each bucket is carried to the elevation of desired discharge.

Other features and objects of the invention that have been attained will appear from the more detailed description to follow with reference to embodiments of the present invention shown in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 of the accompanying drawing shows diagrammatically in side elevation, a rotary kiln according to the present invention;

FIG. 2 of the drawing is an enlarged view in section taken along line lI-II of FIG. 1;

FIG. 3 is an enlarged fragmentary view in section showing a material lifting bucket according to another embodiment of the present invention;

FIG. 4 is an enlarged fragmentary view in section showing a material lifting bucket according to still another embodiment of the present invention; and

FIG. 5 is a fragmentary view taken along line V-V of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing and FIG. 1 in particular, the invention is illustrated as installed in a rotary kiln which comprises a tubular shell 1 having riding rings 2 supported on rollers 3 and a slightly inclined central axis X-Y. The upper end of shell 1 is enclosed by a hood l3 and the lower end of shell 1 is enclosed by a hood 14. The hood 13 has an outlet 15 for hot gases and the ma terial to be heated is introduced into the upper end of kiln 1, through the hood 13, by a pipe 16. The kiln may be tired by fuel through a burner pipe 17 projecting through the lower hood l4 and into shell 1. The burned product discharged into hood 14 may be disposed of in any of the usual ways, such as directly to a cooler (not shown) or to a conveyor for transport to a cooler (not shown). A plurality of material lifting buckets 20 are spaced around and attached to the outer circumference of rotary shell 1 to rotate with shell 1 about the axis X-Y. The buckets 20 will be described in greater detail with reference to FIG. 2.

Referring to FIG. 2 buckets a through 20d are shown which may be of identical construction. With particular reference to bucket 20a, it is shown that the bucket has wall means 22 with a terminal lip 24 attached to shell 1 in alignment with a radial opening 26 thorugh shell 1 and the usual refractory lining 28 with shell 1. Each bucket 20 also has an end wall 30 remote from shell 1. The side wall means 22 and lip 24 have a first portion 32 which comprises the lowermost portion of the side wall and lip of a bucket 20 being carried upwardly by the rotating shell 1 (see bucket 20a on the right hand side thereof as viewed in FIG. 2). The same first portion 32 comprises the uppermost portion of the side wall and lip of a bucket being carried downwardly by the rotating shell 1 (see bucket 200 on the left hand side thereof as viewed in FIG. 2). Each bucket 20a-20d is attached to the shell 1 (see bucket 20a in FIG. 2) with the first portion 32 defining an acute angle Z of perhaps, for example, about 60 with the shell 1 and a material retaining pocket 34 between the first portion 32 of each bucket 20 and its end wall 30. When a bucket, such as bucket 20a in FIG. 2, is on the upturning side of shell 1 the pocket 34 will be below the lip 24 until the bucket is carried to a position well above a horizontal plane through axis X-Y, i.e., the position 20a shown in FIG. 2 by broken lines, and complete emptying of a bucket may not occur until a bucket reaches the uppermost position indicated by bucket 20b in FIG. 2. The side wall means 22 and lip 24 hve a second portion 36 which comprises the uppermost portion of the side wall and lip of a bucket 20 being carried upwardly by the rotating shell 1 (see bucket 20a on the right hand side of shell 1, as viewed in FIG. 2). The same second portion 36 comprises the lowermost portion of the side wall and lip of a bucket being carried downwardly by the rotating shell 1 (see bucket 20c on the left hand side of shell 1 as viewed in FIG. 2). The second portion 36 of each bucket 20 defines an obtuese angle W of perhaps, for example, about 120 degrees with shell 1.

Referring now to FIG. 3, a modified bucket 20 is shown having an end wall 30 that is movable toward and away from shell 1 to regulate the volumetric capacity of a space 40 within the bucket. An adjustable support for end wall 30, is provided that includes a cap 41 on the end wall means 22, and a bracket 42 connected to cap 41 and having a back portion 44 parallel to end wall 30 and radially outward of cap 41. A threaded shaft 46 projects through the back portion 44 and is connected to end wall 30. Adjusting means, shown as a nut 48, is turned on shaft 46 and held in a fixed position between cap 41 and back portion 44 of bracket 42, and when nut 48 is turned shaft 46 and end wall 30 move toward or away from shell 1 to regulate the volumetric capacity of space 40.

Referring to FIGS. 4 and 5, still another modified bucket 20 is shown with flat sided side wall means 22, tapered toward an apex (not shown) radially outward of shell 1 in both a cross-sectional plane, as shown in FIG. 4, and in an axial plane as shown in FIG. 5. This double taper toward an apex (not shown) outwardly of the shell 1 and bucket end wall 30 provides a bucket that will empty completely and rapidly when arriving near or at the top of rotating shell 1.

In the operation of the present invention as described with regard to FIGS. 1 and 2, material enters the upper end of kiln shell 1 through the feed pipe 16 and forms a bed B within the shell 1 (see FIG. 2) which is rotated in the direction indicated by arrows. Material in bed B churns and moves down the incline of shell 1 until it reaches buckets 20 where material passes out of shell 1 through openings 26 and into a bucket in the position illustrated by bucket 20d in FIG. 2. The rotation of shell 1 will carry a filled bucket to the position illustrated by bucket 20a. In the position occupied by bucket 20a, lip 24 is at and above a horizontal plane through axis X-Y but pocket 34 is still below this plane and lip 24, and thus a substantial amount of material is retained in pocket 34. Pocket 34 does not reach the same horizontal plane occupied by the lip 24 until it reaches position 20a indicated by broken lines in FIG. 2, and even then the angle of repose for most materials is sufficiently steep that only a minor portion will begin to spill from the bucket. The bucket will not completely empty until reaching a position such as illustrated by bucket 20b in FIG. 2. Thus the material lifting buckets which are completely external of shell 1, neither interfere with the flow of hot gases from burner 17 through shell 1 to outlet 15 nor are the buckets exposed to the effects of such gases, and the arrangement insures that a substantial portion of the material lifted from the bottom of shell 1 will be lifted high enough to provide a shower of material across substantially the entire diameter of the shell. The smaller the acute angle Z the higher the bucket will travel before spilling and dumping the last of the material out of the pocket to shower back into the shell. The angle Z can be chosen with regard to the angle of repose for a particular material to be processed, to provide an improved curtain of falling material across the rotating shell. Thus, greater exposure of individual particles of material to hot gases is provided by achieving the improved showering curtain of material across the shell and through which the gas must pass. The objects set forth for the present invention have therefore been achieved.

From the foregoing detailed description of the present invention it has been shown how the objects of the present invention have been attained in a preferred manner. However, modification and equivalents of the disclosed concepts such as readily occur to those skilled in the art are intended to be included in the scope of this invention. Thus, the scope of the invention is intended to be limited only by the scope of the claims such as are or may hereafter be, appended hereto.

I claim:

1. An apparatus for treating material with gas having a tubular gas and material confining shell mounted for rotation about a central axis inclined with respect to a horizontal plane to promote material movement through the shell from an upper feed end toward a lower discharge end, and an improvement comprising:

a. a material lifting bucket attached to the outer circumference of the shell to rotate therewith, with the bucket having side wall means with a terminal lip on the end of the side wall attached to the shell, the side wall means and lip being aligned with a radial opening through the shell, and an end wall enclosing an end of the side wall means remote from the shell;

b. the side wall means and lip having a first portion which comprises the lowermost portion of the side wall means and lip when the bucket is on the upward turning side of the rotating shell and which comprises the uppermost portion of the side wall means and lip when the bucket is on the downward turning side of the rotating shell, with said first portion of the side wall and lip being attached to the shell to define an acute angle therebetween and a material retaining pocket between the first portion of the side wall and the bucket end wall which is below the lip when the bucket is on the uptuming side of the kiln and the first portion lip is in a comjustable support for the bucket end wall comprises a 5 bracket having a back portion parallel to the end wall and radially outward thereof, a shaft projecting through the back portion and connected to the end wall, and adjusting means operatively engaging the bracket and men horizontal plane with the centra axis of the 0 shaft to move the shaft and end wall toward and away shell; and

. the bucket end wall is connected to the bucket side walls by an adjustable support operative to move from the lip to regulate the volumetric capacity of the bucket. 

1. An apparatus for treating material with gas having a tubular gas and material confining shell mounted for rotation about a central axis inclined with respect to a horizontal plane to promote material movement through the shell from an upper feed end toward a lower discharge end, and an improvement comprising: a. a material lifting bucket attached to the outer circumference of the shell to rotate therewith, with the bucket having side wall means with a terminal lip on the end of the side wall attached to the shell, the side wall means and lip being aligned with a radial opening through the shell, and an end wall enclosing an end of the side wall means remote from the shell; b. the side wall means and lip having a first portion which comprises the lowermost portion of the side wall means and lip when the bucket is on the upward turning side of the rotating shell and which comprises the uppermost portion of the side wall means and lip when the bucket is on the downward turning side of the rotating shell, with said first portion of the side wall and lip being attached to the shell to define an acute angle therebetween and a material retaining pocket between the first portiOn of the side wall and the bucket end wall which is below the lip when the bucket is on the upturning side of the kiln and the first portion lip is in a common horizontal plane with the central axis of the shell; and c. the bucket end wall is connected to the bucket side walls by an adjustable support operative to move the bucket end wall toward and away from the lip and regulate the volumetric capacity of the bucket.
 2. An apparatus according to claim 1 in which the adjustable support for the bucket end wall comprises a bracket having a back portion parallel to the end wall and radially outward thereof, a shaft projecting through the back portion and connected to the end wall, and adjusting means operatively engaging the bracket and shaft to move the shaft and end wall toward and away from the lip to regulate the volumetric capacity of the bucket. 